Earthquake PA4300 "slave side" (Part 2)

marko

Member
2004-05-08 11:40 am
donnyuk
OK after having success repairing the main side of my beast project I've now been working on the "slave side" of the amp, this is where i'm up to..

I replaced all 12 irfz44n power supplu fets as they were blown and also changed the 5 3300uf 35v caps for the PS, without a remote wire hooked up the amp is pulling a lot of current and one bank of mosfets are getting very hot whilst the other side was not even warm? I can't take any readings off the PWM as I fear some damage may occur..

Mark.
 
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marko

Member
2004-05-08 11:40 am
donnyuk
just checking components around the PWM and Q4 (A1268) has an open circuit on the left to middle leg...


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marko

Member
2004-05-08 11:40 am
donnyuk
Did you find the break?

If so, did that solve the problem?

the remote feeds R7 then ZD3 then Q4, Q4 has a break on this leg, will this cause the power supply to draw a lot of current?




this side of the amp (master) is fully operationl now, I didn't know if it was best to carry on in the same thread with this side but didn't want to confuse anyone!

Mark
 

marko

Member
2004-05-08 11:40 am
donnyuk
OK, I'll try and source some suitable gate resistors tomorrow as I don't have any in th 68-100 range.

I checked the PWM again and now that has equal resistance on 7/9 and 7/10 (about 1k ohm).

the amp still pulls about 40 amps with NO remote wire hooked up, and just one bank of FETS get hot!

thanks for the help so far, much appreciated :)
 
Similar amps use an NPN transistor (Q7 and Q8 in this amp?) to drive the voltage high for the FET drive signal. If that's the case for this amp, that NPN transistor could be defective.

You could try powering the amp up without those transistors. The 56 ohm resistors will keep the FETs off.

I'll go and try this now..

I have now 68 and 82 ohm resistors to try for the gates, would there be any prefered out of these 2?